<template>
<div>
    <h1>当前求和为{{sum}}</h1>
    <select v-model="n">
        <!-- 这里的value直接使用会被解析成字符串，使用v-bind绑定，引号里面会被当成表达式处理 -->
        <option :value="1">1</option>
        <option :value="2">2</option>
        <option :value="3">3</option>
    </select>
    <button @click="increment">+</button>
    <button @click="decrement">-</button>
    <button @click="incrementOdd">当前求和为奇数再加</button>
    <button @click="incrementWait">等一等再加</button>
</div>
</template>

<script>

export default {
    name:'Count',
    data() {
        return {
            n:1, //当前默认选择的数字
            sum:0 // 当前和
        }
    },
    methods: {
        increment(){
            this.sum += this.n
        },
        decrement(){
            this.sum -= this.n
        },
        incrementOdd(){
            if(this.sum % 2){
                this.sum += this.n
            }
        },
        incrementWait(){
            setTimeout(() => {
                this.sum += this.n
            },500)
        },
    },
    
}
</script>
<style scoped>
button{
    margin-left: 5px;
}
</style>